An ultrasound diagnosis apparatus transmits ultrasonic beams to a biological body and receives resulting reflected waves to apply the principle of pulse reflection to the resulting reflected waves thus received, thereby generating an image of biological tissues. The ultrasound diagnosis apparatus has characteristics such as non-invasive, small size, and real-time display and is widely used in medical fields.
In general, sensitivity in a deep portion of the body tends to decrease in medical examinations using the ultrasound diagnosis apparatus. In order to increase the sensitivity in a deep portion of the body, for example, decreasing the frequencies of ultrasonic pulses may be considered, but that also decreases spatial resolution. It may also be considered, for example, to stop using a mode in which harmonic components are visualized (hereinafter referred to as “harmonic imaging mode”) and to start using a normal mode in which the fundamental is visualized, but that does not provide an advantage of reducing artifacts, although the reduction in artifacts is expected in the harmonic imaging mode. As yet another example, increasing acoustic pressure may be considered, but it is difficult to significantly increase the acoustic pressure because of a limitation of mechanical index (MI). When the ultrasound diagnosis apparatus performs contrast imaging, it can increase the acoustic pressure to some extent, but that leads to bubble destruction, whereby the opposite effect may occur such as insufficiently enhanced contrast image. Thus, none of the measures described above can appropriately increase sensitivity in a deep portion of the body.